Dry spinning process



Patented May 26, 1942 DRY srnmmo rnoonss' Leo Ubbelohde,Berlin-Charlottenburg, Germany No Drawing.

Application September 26, 1939,

Serial No. 296,686

23 Claims.

The present invention relates to an improved method of forming productsfrom aqueous solutions of cellulosic material. While the inventioncomprehends the formation of films or sheet products of aqueoussolutions of cellulosic materials, it is particularly adapted for theformation of filaments of cellulosic material such as the xanthogenateof cellulose, or viscose, or to the formation of films of cuprammoniumcellulose.

Heretofore the dry spinning process has been applicable only withrespect to solutions of derivatives of cellulose, but according to thepresent invention the dry spinning process is rendered applicable for.the formation of products from aqueous solutions of cellulose such assolutions of viscose or of cuprammonium cellulose.

According to the present invention the aqueous solutions of celluloseprior to the spinning operation are heated to a temperature below thatat which the cellulosic material contained in the solution willdecompose and the solution while so heated is extruded into anatmosphere of a drying gas.

In carrying out the process according to the present invention anaqueous solution of viscose or other cellulosic material is prepared.The cellulose content of the solution may be normal, that is, about 8%,but in order that the viscosity of the solution will be greater thannormal viscose or cuprammonium spinningsolutionsnthemsolution preferablycontains from to 18% of cellulosic material.

After the aqueous solution of the cellulosic material is formed in theusual manner it is permitted to ripen for a period of from 4 to 5 daysat a temperature of about 20 C., but the ripen- C; and through which theaqueous solution of alkali cellulose is passed at a desired rate,according to the length and the obliquity of the drum and its rotatingspeed. In such cases the drum may be provided with a double wall forreceiving a heat exchange medium and suitably subdivided so that thedesired temperature may be maintained at the difierent parts of thedrum.

After the cellulosic solution has ripened for the desired length of timeit is heated to a temperature preferably between about 40 C. to 0.,although in some instances the temperature may drop as low as 30 C. orbe raised to about 0., although the temperature of the solution i shouldnot be permitted to rise above the latter stated temperature, it isextruded in a well known manner through orifices to form products of thedesired shape. If filaments are to be formed the solution is extrudedthrough the usual spinning nozzles. The material leaving the extrusionorifices passes into a stream of heated air or other gas known to besuitable for drying the extruded products. The air or gas in the cell orchamber into which the products are extruded is preferably at atemperature of about 200 C. at the place where the products enter thechamber. The temperature of the air or gas decreases as the extrudedproducts pass through the chamher and the gases in the middle part ofthe chamber will be at a temperature of between about 150 C. to 180 C.,while in the lower part of the chamber the temperature of the gases willbe between about C. to C., or possibly as low as 100 C. The use of suchelevated temperatures in the cell or chamber is possible due to the factthat the material leaving the extrusion orifices passes through the cellor chamber at a speed such that it does not attain a temperature, beforepassing out of the cell, at which decomposition of the material willtake place.

The carrying out of the method of forming the extruded products asdescribed above has been found to give products of materially betterquality in--that they haVe increased tensile strength and are of moredesirable cross section. In the case of filaments the cross sectionsthereof are of a round or lobulated shape instead of a biscuit-like oralmond-shaped form such as results from present methods of extrudingviscose or cuprammonium spinning solutions. Furthermore, productsproduced by the above described process have improved dyeing and tensileproperties. The nature, and especially the feel of fabrics made fromfilaments in accordance with the present invention are improved.

The air or gas may be introduced into the spinning cell or chamber intowhich the products are extruded by introducing it either into the upperor into the lower part of the spinning cell or chamber, so that the airor gas stream travels either in the same direction of the filament afterits passage. through the extrusion orifices, or in the op ositedirection. Suitable means are provided for maintaining the desired ,ningcell andstill consisting of cellulose xanthogenate, if viscose solutionsare being extemperatures of the air or gas in the different a parts ofthe spinning cell or chamber.

The effects described above are intensified by I the preheating of thecellulosic solution as previously described. The preheating of the cel-7 known composition for use in coagulating or xanthogenate, for example,the bath may contruded, may pass to a coagulating bath of well sist ofmethyl or alkyl alcohol or of diluted organic acids, such as' dilutedacetic acid, or of solutionsof ammonium salts or of salts of solublesulphites, such as sodium sulphite or sodium bisulphite 'or the like.The last mentioned solution is advantageous because the filamentconamount of stretch to'be imparted to the fllaments due to their ownweight, but in most instances it is desired to increase the stretchimparted to the filaments, andthat may be done by a device which removesthe filament from the spinning shaft. The stretch may be furtheraugmented by filament brakes in the spinning cell or chamber or bypassing the filaments between several rollers rotating at differentspeeds. If the filament leaves the spinning nozzle at a speed of 80 to90 meters per minute it will leave the spinning cell or chamber at aspeed of about 200 meters per minute. The filament as it leaves thespinning cell may pass through a thread guide and thereby undergo acertain friction which will give the thread a further stretch so that itwill be wound up at a speed of about 200 to 220 meters per minute. Thefilaments upon leaving the spinning cell will be sufiiciently solid andstrong to permit their being wound up or being regenerated to cellulose.which the filaments are stretched may vary widely. For example, thefilaments may be ,stretched only from about 5% to of their 'length, orfrom about 50% to 1000% of their length at the time when they leave thespinning nozzle.

As described in my application Serial No. 106,141, it is often desirableto crimp or curl the formed filaments and the crimping or curling of thefilaments formed in accordance withthe present invention-may beaccomplished as set forth in my said application and may be performedeither during the regeneration of'the fibers to cellulose or beforeregeneration to cellulose, or even after the regeneration to cellulosehas been performed.

It is also desirable in many instances to cut the filaments into shortstaples of desired length.

The cutting of the filaments into staples may take place, when viscosefilaments are being curled and cut staples for some time in contact withthe regeneration liquid so that tensions and the like within the singlestaples may be compensated. For example, the filaments crimped or curledand cut into small staples of desired length fall into the regenerationliquid, such as a mineral acid bath, from which the cut fibers may betaken for further after treatment.

Further, the filament formed within the spin- The extent to,

slsting of cellulose xanthogenate will in the meantime be purified, thatis, desulphurized. Desulphurizing substances such as sodium sulphite,sodium bisulphite, ammonium sulphide or mixtures of those substances orthe corresponding sulphates, singly or mixed with each other or with theaforementioned substances may be used in aqueous solution or in additionto the before mentioned alcoholic bath. The alcoholic ,.short staples,or, which is preferred, the fiber may be crimped and cut into staplesand then fall into the coagulating and desulphurizing bath andthereafter be regenerated to cellulose.

Substances or materials which are well known in producing common staplefibers or artificial silk may be added to the aqueous solution of thecellulosic material, the addition serving, for example, for matting theproduct and for giving to it a special character or for imparting to theinner structure of the fiber'a special form; for example, for producingsmall hollow spaces in the fiber or for giving it a faveolate structure.For influencing the inner structure of the filament in this way anaddition of starch may be made either in theform of a powder or of asolution of undisintegrated starch. When starch is added to the aqueoussolution of the cellulosic material it may be added in the amount offrom about 0.5% to 15% calculated on the cellulosic content of thesolution.

Other substances known as additional substances in spinning artificialsilk also may be added to the cellulosic solution. Such substances maybe.removed altogether or partly, so that the inner structure of thefilament will show numerous hollow spaces. When adding only a smallquantity of the substances mentioned before, the faveolate structurewill decrease to microscopic fineness.

Sharp edged materials of a size to impart a roughened or uneven surfaceto the filaments may be added to the'aqueous cellulosicsolution. Suchsubstances may consist of pulverized fibers of any kind or infusorialearth or other substances of a similar character. The addition of suchsubstances is of special advantage in improving thespinning propertiesof the filaments produced and "when added should be in an amount of fromabout 0.1% to 19% calculated on the cellulose content of the cellulosicsolution.

The curly or crimpy state of the filaments produced as described abovemay be rendered still more durable, which is of great importance,espenatural or artifical resins or substances which are able to formartificial resins to the viscose and then condensing or pulverizing orhardening viscose deniers, while the spun rope had a denier of of thefilament, or after the forming and curling resin-like material, may beperformed either by chemical or by physical methods; or by both.

The filament, which may still consist of vis-' cose or of cuprammonium,or may even already be transformed into regenerated cellulose, is passedthrough a pair of fluted rollers which render it curly, as described inmy aforesaid application. The fluted rollers may be maintained at roomtemperature or may be heated to a temperature of about 30 C. or 60 C. oreven higher, for example, to temperatures between 70 C. and 150 C. Therollers may be mounted within a so-called spinning bath to promote thecoagulation of the viscose or its regeneration to cellulose, thetemperature of the rollers then of course not being above the boilingpoint of the bath used and normally being below that temperature, or therollers may only be sprinkled with the, liquid which normally would formthe spinning bath. In performing the process in this manner, thefilament, while entering between the fluted or the like rollers, willundergo a stretching during the curling and coagulating, or during theprocess of regenerating the cellu lose. lose may be performed by gasessuch as carbon dioxide, sulphur dioxide or the like which also may beheated, as well as the rollers themselves. The curling or crimping ofthe filament and the regeneration of the cellulose may take placesuccessively, although in order to obtain aparticular efiect, it ispreferred that the curling or crimping of the filaments and theregenerating of the cellulose take place simultaneously. It is to beunderstood that although reference ,is frequently herein made tosolutions of viscose,

cuprammonium may equally well be used; both substances having normally ahigh concentration of cellulose which may rise'to 30% by weight or evenmore, although normally lower concentrations between about 10% and 25%of cellulose will be used. 1

According to one example of carrying out the present process a viscosesolution containing 16% of cellulose was prepared from aso-calledartificial silk pulp. The alkali cellulose made in the usual manner wasripened for a period of three days at a temperature of about 18 C. Thealkali cellulose was treated in the usual manner with carbon bisulphideand the xanthogenate formed was dissolved in such a quantiy of purewater that 16% of cellulose was found in the resulting solution. Theviscosity of the solution thus formed was rather high and a steel ballof a diameterof f/g of an inch took about 60 seconds to sink below thesurface so that it was no longer visible. The viscose was then ripenedfor five days at a temperature of about 20 C. and was then filtered anddearated, and after being raised to a temperature of about 40 C. waspassed through a spinning nozzle under a pressure of 8 atmospheres. Fromthe spinning ozzle the extruded filaments passed into a spinning cell inwhich the temperature in the upper part was about 200 C. and in themiddle part between 150 C. and 180 C. and in the lower part between 110C. and 140 C. The filaments entered the spinning nozzle at a speed of 80to 90 meters per minute and left the spinning cell at a, speed ofbetween 200 and 220 meters per minute.- The titer of a single filamentwas between .4 and Of course, the regenerating of the celluabout 200.The temperature in the upper part of the spinning cell was maintained ata temperature of about 200 C: by a stream of air blown into the upperpart thereof 'at a speed of from about 0.8 to 1 meter per second so thatthe speed of the air stream was slower than the spinning speed of thefilament. The'filaments' were stretched, curled. and crimped andregenerated as described above.

This application is a continuation-impart of my application forDry-spinning process, Serial No. 42,053, filed September 25, 1935.

I claim:

1. A process for forming products from aqueous solutions of cellulosicmaterial which comprises heating a solution of such material to atemperature between approximately 30 C. and 80 C., thereafter, and whilethe solution is at such temperature, forming the solution intosubstantially the shape of the final product and passing the same into acurrent of a gaseous drying atmosphere, and regenerating the formedproduct to cellulose.

2. A process ,for forming products from aqueous solutions of cellulosicmaterial which comprises heating a solution of such material to atemperature'between approximately 40 C. and C., thereafter, and whilethe solution is at such temperature, forming the solution intosubstantially the shape of the final product and stantially the shape ofthe final product and passing the same into a current of a gaseousdrying atmosphere, stretching the product, and regenerating the formedproduct to cellulose.

4. A process for forming products from aqueous solutions'of cellulosicmaterial which comprises heating a solution of such material to atemperature between approximately 40 C. and 50 C., thereafter, and whilethe solution is at such temperature, forming the solution intosubstantially the shape of the final product and passing the same into acurrent of a gaseous drying atmosphere, stretching the product, andregenerating the formed product to cellulose.

5. A process for forming products from aqueous solutions of cellulosicmaterial which comprises heating a solution of such material to atemperature of between about 30 C. and 80 C thereafter, and while thesolution is at such tempera- *ture, forming the solution intosubstantially the shape of the final product, passing said product intoa current'of'a gaseous drying atmosphere decreasing in temperature fromabout 200 C. to

- formed will be decomposed stretching the prodsolutions of cellulosicmaterial which comprises heating a solution of such material to atemperature of between about 40 C. and 50 0., there..

after, and whilethe solution is at 'such temperature, forming thesolution into substantially the filaments to cellulose.

shape of the final product, passing said product into a current of agaseous drying atmosphere decreasing in temperature from about 200 0. to

about 100 0., removing said product from said gaseous drying atmospherebefore it attains a temperature at which the material of which it isformed will be decomposed stretching the prod-' uct. andregenerating theformed product to cellulose. v

7. A process for dry spinning artificial filaments of aqueous solutionsof cellulosic material which comprises heating a solution of suchmaterial to a temperature between about 30 0. to 80 0.,

thereafter, and while the solution is'at such a temperature pressing thesame through'fin'e orifices into a current of a drying atmosphere above100' 0., removing the resulting filaments from said drying atmospherebefore they attain a temperature at which the material of which they areformed will decompose, and regenerating the formed filaments tocellulose,

-.8. A process for dry spinning ments of aqueous solutions of cellulosicmaterial artificial fila- Q which comprises heating a solution of suchmatethey are formed will decompose, stretching the formed filaments,and-regenerating the formed 9. A process for dry spinning artificialfilaments of aqueoussolutions of cellulosic material which comprisesheating a solution of such material to a temperature between about 40 0.to 50 0., thereafter, and while the solution is at such a temperaturepressing the same through fine orifices into a current of a dryingatmosphere 40 C. and 50 0., thereafter, and while. the viscose solutionis at such temperature. pressing it through line orifices into a currentof a drying atmosphere gradually decreasing in temperature from about200 0. to about 110 0., removing the 7 resulting filaments from saiddrying atmosphere before they attain a temperature at which the materialof which they are formed will decompose stretching the filaments, andregenerating the filamer ts to cellulose.

13. A process for forming artificial filaments ments, and regeneratingthe formed filaments to cellulose.

14. A process for forming artificial filaments of aqueous solutions ofcellulosic material which comprises forming an aqueous solutioncontaining from 15% to 18% of'cellulosic material, ripabove 100 0..removing the resulting filaments from said drying atmosphere before theyattain a temperature at which the material of which they are formed willdecompose, and regenerating the formed filaments'to cellulose.

' 10. Aprocess for dry'spinning artificial filaments of aqueoussolutionsof cellulosic material which comprises heating a. solution ofsuch material to a temperature between about 40 C. to 50 0., thereafter,and while the solution is at sucha temperature pressing the samethroughfine orifices into a current of a drying atmosphere above 100 0.,removing the resulting filaments from said drying atmosphere before theyattain a temperature at which the material of which they are formed willdecompose, stretching the formed filaments, and regenerating the formedfilaments to cellulose.

11; A process for dry spinning artificial filaments of viscose whichcomprises heating a solution of viscose to a temperature between about30 0. and.80 0., thereafter, and while the viscose solution is at suchtemperature, pressing it through fine orifices into a current of adrying atmosphere gradually decreasing in ,temperature from about 200 0.to about 110 0., removing the resulting filaments from said dryingatmosphere before they attain a temperature at which thematerial ofwhich'they are formed will decompose stretching the filaments, andregenerating the filaments tocellulose. V g

12. A process for dry spinning artificial filaments of viscose whichcomprises heatinga soluening such solution for a period from about fourdays to five days at a temperature from about 20 C. to about 30 0.,heating the ripened solution of cellulosic material 'to a temperature ofbetween about 40 0. and about 50 0., thereafter, and while the solutionis at such temperature, pressing it through fine orifices into a currentof a drying atmosphere, stretching the resulting filaments, andregenerating the formed filaments to cellulose.

15. A process for forming products from aqueous solutions of cellulosicmaterial which comprises heating a solution of such material to atemperature between approximately 30 0. and

'80" 0., thereafter, and while the solution is at.

such temperature, forming the solution into substantially the shape ofthe final product and passing the same into a current of a gaseousdrying atmosphere, and regenerating the formed product to cellulose.

16. A process for forming products from aqueous solutions of cellulosicmaterial which comprises heating a solution of such material to atemperature between approximately 40 0. and- 50" 0., thereafter, andwhile the solution is at such temperature, forming the solution intosubstantially the shape of-the final product and passing the same into acurrent of a gaseous drying atmosphere, and regenerating the formedproduct to cellulose.

17. A process for dry spinning artificial filaments of aqueous solutionsof cellulosic material which comprises heating a solution of suchmaterial to a temperature between about 30 0. to 80C., thereafter, andwhile the solution is at sucha temperature pressing the same throughfine orifices into a current of a drying atmosphere, and regeneratingthe formed filaments to cellulose.

18. A process for dry spinning artificial filaments of'a aqueoussolutions of cellulosic material which comprises heating a solution ofsuch material to a temperature between about 40 0. to 50 0., thereafter,and while the solution is at such a temperature pressing the samethrough fine tion of viscose to a temperature between about orificesinto a current of a drying atmosphere,

. and regenerating the formed filaments to cellulose.

19. A process for dry spinning artificial filaments of aqueous solutionsof cellulosic material which comprises heating a solution of suchmaterial to a temperature between about 40 C.

' into a current ofa drying atmosphere gradually decreasing intemperature from about 200 C. to 110 C., stretching the resultingfilaments, cutting said filaments into short staples, and regeneratingthe short staples to cellulose.

21. A process for forming artificial filaments which comprises formingan aqueous solution of cellulosic material, containing starch in aquaned at such temperature through. fine orifices into a current of adrying atmosphere. stretching the resulting filaments, and regeneratingthe filaments to cellulose;

22. A process for forming artificial filaments which comprises formingan'aqueous solution of cellulosic material containing a resin dissolvedtherein, heating said solution to a temperature between about 40 C. toabout 50 C., pressing tity of from about 0.5% to 15%'calculated on thecellulose content of the solution, heating said solution to atemperature between about C. to C., passing said solution while heatsaidsolution while at said temperature through fine orifices into a currentof a drying atmosphere, stretching the resulting filaments, andregenerating the filaments to cellulose and hardening the resincontained therein.

23. A process for forming artificial filaments which comprises forming"an aqueous solution or cellulosic material containing therein adissolved natural resin, heating said solution to a temperature betweenabout 30 C. to'80 C., pressing said solution through fine orifices intoa current of a drying atmosphere, stretching the resulting filaments,-curling or crimping said filaments, cutting said curled or crimpedfilaments into staples of desired length, regenerating said staples tocellulose, and hardening the added natural resin.

\ LEO UBBELOHIDE.

